Question

Obtuse angle between lines y = -2 and y = x + 2 is :

(A) 145°

(B) 150°

(C) 135°

(D) 120°

Answer 1

Answer is (C) 135°

comparing y = -2x with y = m₁x + c₁
m₁ = 0

comparing y = x + 2 with y = m₂x + c₂
m₂ = 1

Angle between both lines

When tan θ = +1 then θ = 45°

when tan θ = -1 then θ = 135°